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Inner Mongolia University (2021)

Effects of Mowing and Nutrient Addition on Ecological Stoichiometry of Typical Steppe in Inner Mongolia

胡锦香

Titre : Effects of Mowing and Nutrient Addition on Ecological Stoichiometry of Typical Steppe in Inner Mongolia

Auteur : 胡锦香

Grade : Master’s Theses 2021

Université : Inner Mongolia University

Résumé
Carbon(C),nitrogen(N)and phosphorus(P)are the three most important elements in the process of plant growth and development,and even play an important role in the structure and function of the whole ecosystem.Ecological stoichiometry is one of the important functional traits of plants,which is closely related to plant growth.Clipping and nutrient addition are two ways of grassland management.Clipping potentially affects the absorption of nutrients by plants by changing the light environment,soil environment and reducing nutrient return.Nutrient addition can potentially affect the absorption of nutrients by plants by supplementing the nutrients necessary for plant growth.Both of them may affect the ecological stoichiometric characteristics of plants and change plant growth to a certain extent.Although many studies have reported the effects of different grassland uses on the stoichiometric characteristics of plants,few studies have focused on the effects of different grassland uses on the stoichiometric characteristics of plants at the time scale.The climate of temperate grassland fluctuates significantly between seasons and years.In this context,it is not clear whether the response of plants to nutrient uptake and ecological stoichiometry to various grassland use patterns is stable or changes with the time fluctuation of climate.For this reason,we carried out three years of cutting and nutrient addition experiments on the typical steppe of Inner Mongolia.At the community level and species level,the inter annual and inter seasonal differences of leaf stoichiometry(C,N,P,C:N,C:P,N:P)of dominant species Leymus chinensis,Stipa krylovii and Cleistogenes spuarrosa were studied.The results are as follows(1)At the species level,the responses of leaf stoichiometry to clipping and nutrient addition were generally consistent : Clipping increased the leaf N content of the three plants by 19.93%、10.57%、35.99%,respectively,and increased the leaf P content of Leymus chinensis and Cleistogenes spuarrosa by 19.22% and 15.77%,respectively.In addition,clipping increased leaf N:P ratios,decreased leaf C:N and C:P ratios,while N addition promoted leaf N content and leaf N:P and P addition promoted leaf P content.The three grasses all responded significantly to clipping and nutrient addition in wet years.There was no significant interaction between clipping and nutrient addition on plant stoichiometry at the species level.(2)On the whole,the effects of clipping and nutrient addition on ecological stoichiometry at the community level were similar to those at the species level(Leymus chinensis and Stipa kryloii),but the effects at the community level were smaller.(3)Clipping has inconsistent effects on the height and biomass of the three dominant species Clipping significantly reduced the height of Leymus chinensis and Stipa krylovii,but had no significant effect on the height of Cleistogenes spuarrosa.Clipping increased the aboveground biomass of Cleistogenes spuarrosa and Stipa krylosii,but significantly decreased the biomass of Leymus chinensis.(4)In the late growing season,clipping and nutrient addition showed a more significant response to the stoichiometric characteristics of plants.Clipping significantly increased the leaf P content of Leymus chinensis and Cleistogenes spuarrosa by 1.54% and 17.09%,and promoted the leaf N content of the three plants16.43%、19.05% and 8.02%,and decreased the C:N,but after nutrient addition,the effect of clipping on the leaf N content and C:N was weakened.During the whole growing season,there was almost no significant seasonal difference in leaf C content,while leaf C:P and N:P decreased.At the community level,the responses of plant ecological stoichiometry to clipping and nutrient addition were similar to those at the species level,but the overall responses were weak.The above results indicate that the ecological stoichiometric characteristics of typical grassland plants have a significant response to both mowing and nutrient addition,and there are significant differences in time

Mots clés : Ecological stoichiometry ;Clipping;Nutrient addition ;Seasonal dynamics ;Interannual variability ;

Présentation (CNKI)

Page publiée le 1er novembre 2021